Conventional liquid enclosures for housing artificial fish are available in the marketplace. One of the purposes of these products is to provide amusement and relaxation for the observer without having to maintain live creatures or plants. Living creatures and plants inherently foul the liquid of liquid enclosures have an inherent need to be fed or fertilized, and have an inherent difficulty in being kept alive. Furthermore, living creatures may have a tendency to outgrow a liquid enclosure depending on its size.
U.S. Pat. No. 6,665,964 to Klotz (hereinafter “Klotz”) describes the use of electromagnets, optical sensors, and liquid flow to enable movement of an artificial fish within a liquid enclosure. In Klotz, liquid pumps act to move artificial fish around a tank of liquid. As the fish move within the enclosure, an optical sensor senses when a fish swims by, and when the sensor senses the nearness of the fish to an electromagnet, the electromagnet is turned on. Depending on the orientation, this will either repulse or attract the fish, causing a sudden movement of the fish.
However, the embodiments described in Klotz do not result in realistic movement of the fish. For example, live fish almost always have some erratic motion, rarely repeat the same motion many times, and rarely swim in a straight line. Conventional artificial fish tanks such as that described in Klotz fail to accurately simulate the erratic motion of live fish. Some conventional embodiments use mechanically rotating permanent magnets as control magnets to pulse and reverse a magnetic field generated in the tank. This provides motion of the fish, but does not provide sufficiently complex control that is needed for more life-like motion of the fish. A static magnetic field or a pulsed but non-reversing magnetic field such as that described in Klotz is less able to simulate erratic motion, reversing direction, and turning actions. Further, conventional designs do not utilize a reversing-field electromagnet or precise magnetic field control, and thus the fish movements are not sufficiently realistic.